Central to Piaget's theory of intellectual development is the view that, in the first six months of life, "out of sight, out of mind" captures the sense in which infants are aware of objects. During the next year, infants come to conceptualize objects as permanent entities which exist when out of view. Recent studies suggest that 5 month olds are aware of objects in the latter sense. A series of studies are proposed, involving the hiding of people and things, to evaluate the relative merits of the conflicting claims.